Molybdenum-oxo-sulfide quantum dot-based nanocarrier: Efficient generation of reactive oxygen species via photo/chemodynamic therapy and stimulus-induced drug release

The fabrication of multifunctional nano-therapies has increased gradually to strengthen the therapeutic performance and minimize adverse effects of traditional cancer treatment strategies. Currently, we have designed a facile preparation drug-loaded nanocarrier for multimodal cancer therapy upon external stimuli. First, defect-rich molybdenum oxo-sulfide (MoOxS2-x) quantum dots (QDs) was synthesized via rapid biomineralization techniques with superior optical quantum yield reaching upto 37.28%. The presence of the Fenton ion, Mo+IV/+VI, enables MoOxS2-x QDs to efficiently catalyze peroxide solutions to produce •OH radicals for chemodynamic treatment (CDT) and also deactivate the intracellular glutathione (GSH) enzymes through redox reaction for boosted reactive oxygen species (ROS)-mediated therapies. In addition, upon laser combination, MoOxS2-x QDs generate ROS for photodynamic therapy (PDT). Also, due to a large amount of sulfide content, MoOxS2-x QDs showed excellent H2S gas release in acidic pH for cancer gas therapy. Then, MoOxS2-x QDs was further conjugated with ROS-responsive thioketal linked Camptothecin (CPT-TK-COOH) drug, forming a multitargeted MoOxS2-xCPT anticancer agent with better drug-loading efficiency (38.8%). After triggering the ROS generation through the CDT and PDT mechanisms, the thioketal linkage was disrupted, releasing up to 79% of the CPT drug in 48 h. Besides, in vitro experiments verified that MoOxS2-x QDs possess higher biocompatibility with 4T1 and HeLa cells but also showed considerable toxicity in the presence of laser/H2O2, resulting in 84.45% cell death through PDT/CDT and chemotherapeutic effects. Therefore, the designed MoOxS2-xCPT exhibited outstanding therapeutic benefits for image-guided cancer therapy.